Primary Production

Bottom-up control on PCZ: Primary Producers

Because of sea-ice, the timing and partitioning of spring primary production differs between the northern and southern shelves. In addition, the phytoplankton community shifts seasonally from one dominated by diatoms in the spring to one dominated by flagellates in the summer.  This shift is driven, in part, by the seasonal drawdown of nutrients and increased water temperatures, both of which favor growth of flagellates.  Studies in other sub-polar shallow shelf systems suggest that climate warming can result in shifts from diatoms to flagellates during the spring bloom when nutrients are high, and an overall reduction in the magnitude of the spring bloom leading to poorer quality food for LCZ. This can only be evaluated by synthesis of extant datasets.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hypothesis 2.1  LCZ size, distribution and standing stocks are controlled by the partitioning of primary production between the benthic and neritic ecosystems. 

Hypothesis 2.2  LCZ size, distribution and standing stocks are controlled by the timing and duration of phytoplankton blooms rather than total annual primary production. 

Question 2.1 Does temperature impact the relationships between phytoplankton composition, net primary production and its partitioning between benthic and neritic systems in the Bering Sea in a manner similar to other temperate / sub-polar coastal seas?

Question 2.2 Do multi-year periods of warm water temperatures reduce annual system NPP relative to multi-year cold periods, thereby reducing carbon and energy flow to higher trophics?

Question 2.3 Does increasing water temperature reduce the relative contribution of summer NPP to annual NPP and thus the overwintering success of higher trophic levels?

Question 2.4 How does increasing water temperature impact the fraction of primary production consumed by LCZ and euphausiids?